JP2642972B2 - Hydraulic circuit of switching valve for attachment - Google Patents
Hydraulic circuit of switching valve for attachmentInfo
- Publication number
- JP2642972B2 JP2642972B2 JP63320370A JP32037088A JP2642972B2 JP 2642972 B2 JP2642972 B2 JP 2642972B2 JP 63320370 A JP63320370 A JP 63320370A JP 32037088 A JP32037088 A JP 32037088A JP 2642972 B2 JP2642972 B2 JP 2642972B2
- Authority
- JP
- Japan
- Prior art keywords
- switching valve
- attachment
- valve
- hydraulic pump
- hydraulic
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2221—Control of flow rate; Load sensing arrangements
- E02F9/2239—Control of flow rate; Load sensing arrangements using two or more pumps with cross-assistance
-
- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F9/00—Component parts of dredgers or soil-shifting machines, not restricted to one of the kinds covered by groups E02F3/00 - E02F7/00
- E02F9/20—Drives; Control devices
- E02F9/22—Hydraulic or pneumatic drives
- E02F9/2278—Hydraulic circuits
- E02F9/2292—Systems with two or more pumps
Landscapes
- Engineering & Computer Science (AREA)
- Mining & Mineral Resources (AREA)
- Civil Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Structural Engineering (AREA)
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- Operation Control Of Excavators (AREA)
- Fluid-Pressure Circuits (AREA)
Description
【発明の詳細な説明】 〔産業上の利用分野〕 この発明は、土木建設機械の油圧回路に係り、特にア
タッチメントを備える場合のアタッチメント用切換弁の
油圧回路の改良に関する。BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydraulic circuit of a civil engineering and construction machine, and more particularly to an improvement in a hydraulic circuit of an attachment switching valve when an attachment is provided.
従来、土木建設機械、特にパワーショベルの油圧回路
においては、その操作性の便宜から、例えば第１の油圧
ポンプにより、旋回、アーム、走行（左側）の制御を行
い、第２の油圧ポンプにより、ブーム、バケット、走行
（右側）の制御を行うよう構成したものが知られてい
る。しかるに、近年この種のパワーショベルでは、アタ
ッチメントとして油圧ブレーカや油圧ベンチャー等を付
加することから、その油圧回路にアタッチメント用切換
弁を常備する傾向にある。この場合、前述したように、
パワーショベルの油圧回路では、油圧ポンプが旋回系と
ブーム系に分けられているため、アタッチメント用切換
弁はいずれかの切換弁グループ（制御弁）内に設置され
る。2. Description of the Related Art Conventionally, in a hydraulic circuit of a civil engineering construction machine, particularly a power shovel, for convenience of operation, for example, a first hydraulic pump controls turning, an arm, and traveling (left side), and a second hydraulic pump controls the turning, arm, and traveling (left side). There is known one configured to control a boom, a bucket, and traveling (right side). However, in recent years, in this type of power shovel, since a hydraulic breaker, a hydraulic venture, or the like is added as an attachment, a switching valve for the attachment tends to be always provided in the hydraulic circuit. In this case, as described above,
In the hydraulic circuit of the power shovel, since the hydraulic pump is divided into a swing system and a boom system, the attachment switching valve is installed in one of the switching valve groups (control valves).
例えば、第３図は、従来のアタッチメント用切換弁を
常備したパワーショベル等の油圧回路の構成例を示すも
のである。第３図において、参照符号10は第１の油圧ポ
ンプを示し、12は第２の油圧ポンプを示す。第１の油圧
ポンプ10には、旋回用切換弁14、アーム用切換弁16、走
行（左側）用切換弁18、バイパス開閉弁20がそれぞれ接
続されて第１の制御弁22を構成している。また、第２の
油圧ポンプ12には、ブーム用切換弁24、バケット用切換
弁26、アタッチメント用切換弁28、走行（右側）用切換
弁30がそれぞれ接続されて第２の制御弁32を構成してい
る。この場合、前記アタッチメント用切換弁28は、第４
図に示すように、第２の油圧ポンプ12に接続された供給
油路34が切換弁内部油路36と連通し、スプール38の操作
によってそれぞれ給排ポート40、42を介してアタッチメ
ントとの油路の接続を行うよう構成される。なお、参照
符号44、46、48はそれぞれセンタバイパスを示す。For example, FIG. 3 shows an example of the configuration of a hydraulic circuit such as a power shovel or the like that always has a conventional attachment switching valve. In FIG. 3, reference numeral 10 denotes a first hydraulic pump, and 12 denotes a second hydraulic pump. The first hydraulic pump 10 is connected with a switching valve 14 for turning, a switching valve 16 for an arm, a switching valve 18 for traveling (left side), and a bypass opening / closing valve 20 to constitute a first control valve 22. . The second hydraulic pump 12 is connected with a boom switching valve 24, a bucket switching valve 26, an attachment switching valve 28, and a traveling (right) switching valve 30 to form a second control valve 32. doing. In this case, the attachment switching valve 28 is
As shown in the figure, a supply oil passage 34 connected to the second hydraulic pump 12 communicates with the switching valve internal oil passage 36, and the operation of the spool 38 allows the oil to be connected to the attachment via supply / discharge ports 40 and 42, respectively. It is configured to make road connections. Reference numerals 44, 46, and 48 indicate center bypasses, respectively.
このように、従来においては、アタッチメント用切換
弁を旋回系（第１の制御弁22）またはブーム系（第２の
制御弁32）を構成する油圧回路のいずれの制御弁側に常
備させても問題はなかった。As described above, in the related art, the attachment switching valve is always provided on the control valve side of the hydraulic circuit constituting the swirling system (first control valve 22) or the boom system (second control valve 32). There was no problem.
しかしながら、近時アタッチメントの種類も増加し、
特殊な場合には、アタッチメントと該アタッチメント用
切換弁が付加されている制御弁内の他の切換弁に接続さ
れたアクチュエータとをそれぞれ独立に操作する要求が
生じるようになった。However, the types of attachments have recently increased,
In special cases, there has been a demand for independently operating the attachment and the actuator connected to another switching valve in the control valve to which the attachment switching valve is added.
例えば、ブーム系の制御弁にアタッチメント用切換弁
を常備した油圧回路において、バケットとアタッチメン
トとをそれぞれ独立して操作する場合等である。このよ
うな場合、同一の油圧ポンプに接続したアクチュエータ
をそれぞれ独立して操作することは困難である。なお、
バンクタイプの制御弁では、他の油圧ポンプ側にアタッ
チメント用切換弁を接続することも可能であるが、一般
的なモノブロックタイプの制御弁では、例えば第５図に
示すように、一方の油圧系に常備されたアタッチメント
用切換弁を使用することなく、他方の油圧系に別に設け
たアタッチメント用切換弁を使用してアタッチメントを
操作しなければならない。For example, in a hydraulic circuit in which a boom-based control valve is provided with an attachment switching valve, the bucket and the attachment are independently operated. In such a case, it is difficult to independently operate the actuators connected to the same hydraulic pump. In addition,
In a bank type control valve, it is possible to connect an attachment switching valve to the other hydraulic pump side. However, in a general monoblock type control valve, for example, as shown in FIG. The attachment must be operated using an attachment switching valve provided separately in the other hydraulic system, without using the attachment switching valve normally provided in the system.
すなわち、第５図は、第３図に示すように、第２の油
圧ポンプ12で構成されるブーム系にアタッチメント用切
換弁を常備した油圧回路であって、第１の油圧ポンプ10
に別のアタッチメント用切換弁34を接続し、バイパス開
閉弁20の操作によって前記第１の油圧ポンプ10の圧油を
前記アタッチメント用切換弁34を介して所要のアタッチ
メントへ供給するよう構成したものである。これによ
り、バケットとアタッチメントとをそれぞれ独立して操
作することができる。しかし、この場合には、前記ブー
ム系に常備したアタッチメント用切換弁28は全く機能せ
ず、無駄な設備となる難点がある。That is, FIG. 5 shows a hydraulic circuit in which a switching valve for attachment is provided in a boom system constituted by a second hydraulic pump 12 as shown in FIG.
Is connected to another attachment switching valve 34, and the pressure oil of the first hydraulic pump 10 is supplied to a required attachment via the attachment switching valve 34 by operating the bypass opening / closing valve 20. is there. Thus, the bucket and the attachment can be operated independently of each other. However, in this case, the attachment switching valve 28 always provided in the boom system does not function at all, and there is a problem that the equipment becomes useless.
そこで、本発明の目的は、一方の油圧ポンプ側にバイ
パス開閉弁を備えると共に他方の油圧ポンプ側にアタッ
チメント用切換弁を常備した油圧回路において、前記他
方の油圧ポンプ側におけるアタッチメントと他のアクチ
ュエータとをそれぞれ独立させて駆動制御する際に、簡
単な構成でしかもアタッチメント用切換弁を有効に使用
してそれぞれ別の油圧ポンプの圧油により操作すること
ができる省スペースで低コストに製造し得るアタッチメ
ント用切換弁の油圧回路を提供するにある。In view of the above, an object of the present invention is to provide a hydraulic circuit having a bypass opening / closing valve on one hydraulic pump side and a switching valve for attachment on the other hydraulic pump side, wherein the attachment and the other actuator on the other hydraulic pump side are used. Attachments that can be manufactured at low cost with a simple configuration and can be operated with the hydraulic oil of separate hydraulic pumps by using the switching valve for attachment effectively, when controlling the drive independently of each other To provide a hydraulic circuit for a switching valve.
本発明に係るアタッチメント用切換弁の油圧回路は、
第１の油圧ポンプに接続されてバイパス開閉弁を備える
第１の制御弁と、第２の油圧ポンプに接続されてアタッ
チメント用切換弁を含む複数の切換弁を備える第２の制
御弁とからなる油圧回路において、 前記アタッチメント用切換弁のセンタバイパスを常時
開とすると共に第２の油圧ポンプと接続された供給油路
から前記アタッチメント用切換弁への油路を常時閉とす
るよう構成し、 前記アタッチメント用切換弁の供給油路を第２の制御
弁の外部に設けてこれを第１の油圧ポンプに接続された
供給油路と接続し、 前記アタッチメント用切換弁と連動させて前記バイパ
ス開閉弁を操作し該アタッチメント用切換弁の供給油路
に第１の油圧ポンプの圧油を供給するよう構成すること
を特徴とする。The hydraulic circuit of the attachment switching valve according to the present invention,
It comprises a first control valve connected to the first hydraulic pump and having a bypass on-off valve, and a second control valve connected to the second hydraulic pump and having a plurality of switching valves including an attachment switching valve. In the hydraulic circuit, a center bypass of the attachment switching valve is always opened, and an oil passage from a supply oil passage connected to a second hydraulic pump to the attachment switching valve is always closed, and A supply oil passage for the attachment switching valve is provided outside the second control valve and connected to a supply oil passage connected to the first hydraulic pump, and the bypass on-off valve is operated in conjunction with the attachment switching valve. To supply the pressure oil of the first hydraulic pump to the supply oil passage of the attachment switching valve.
本発明に係るアタッチメント用切換弁の油圧回路によ
れば、第１の油圧ポンプに接続されてバイパス開閉弁を
備える第１の制御弁と、第２の油圧ポンプに接続されて
アタッチメント用切換弁を含む複数の切換弁を備える第
２の制御弁とからなる油圧回路において、前記第２の油
圧ポンプ側に設けられるアタッチメントと他の切換弁に
接続されるアクチュエータとをそれぞれ独立して操作す
る場合、前記アタッチメント用切換弁の操作に伴いバイ
パス開閉弁が操作されて、第１の油圧ポンプの圧油が外
部油路を介してアタッチメント用切換弁に供給され、該
アタッチメント用切換弁と他のアクチュエータ用切換弁
とをそれぞれ別の油圧ポンプの圧油で有効に制御するこ
とができる。According to the hydraulic circuit of the attachment switching valve according to the present invention, the first switching valve connected to the first hydraulic pump and including the bypass on-off valve, and the switching valve for attachment connected to the second hydraulic pump are provided. In a hydraulic circuit including a second control valve including a plurality of switching valves, the attachment provided on the second hydraulic pump side and the actuator connected to another switching valve are operated independently. The bypass on-off valve is operated in accordance with the operation of the attachment switching valve, and the pressure oil of the first hydraulic pump is supplied to the attachment switching valve via the external oil passage, and the attachment switching valve and another actuator The switching valve and the switching valve can be effectively controlled by the pressure oil of different hydraulic pumps.
次に、本発明に係るアタッチメント用切換弁の油圧回
路の実施例につき、添付図面を参照しながら以下詳細に
説明する。Next, an embodiment of a hydraulic circuit of an attachment switching valve according to the present invention will be described in detail with reference to the accompanying drawings.
第１図は、本発明油圧回路の一実施例として、パワー
ショベルのアタッチメント用切換弁に適用した場合の油
圧回路を示す。従って、説明の便宜上前述した第３図に
示す従来の油圧回路の同一の構成部分については、同一
の参照符号を付しその詳細な説明は省略する。すなわ
ち、第１図に示す実施例において、第１の油圧ポンプ10
には、旋回用切換弁14、アーム用切換弁16、走行（左
側）用切換弁18、バイパス開閉弁20がそれぞれ接続され
て第１の制御弁22を構成している。また、第２の油圧ポ
ンプ12には、ブーム用切換弁24、バケット用切換弁26、
アタッチメント用切換弁28、走行（右側）用切換弁30が
それぞれ接続されて第２の制御弁32を構成している。こ
れらの構成は、従来の油圧回路と同じである。FIG. 1 shows, as an embodiment of the hydraulic circuit of the present invention, a hydraulic circuit applied to a switching valve for attachment of a power shovel. Accordingly, for convenience of explanation, the same components of the conventional hydraulic circuit shown in FIG. 3 described above are denoted by the same reference numerals, and detailed description thereof will be omitted. That is, in the embodiment shown in FIG.
The first control valve 22 is formed by connecting the swing switching valve 14, the arm switching valve 16, the traveling (left) switching valve 18, and the bypass on-off valve 20 to each other. The second hydraulic pump 12 has a boom switching valve 24, a bucket switching valve 26,
The attachment switching valve 28 and the traveling (right) switching valve 30 are connected to each other to form a second control valve 32. These configurations are the same as the conventional hydraulic circuit.
しかるに、本実施例においては、第２図に示すよう
に、アタッチメント用切換弁28に設けられる切換弁内部
油路36を、第２の油圧ポンプ12（ブーム系）と接続され
る供給油路34とは遮断して常時閉とし、後述する外部配
管と接続可能な圧油供給ポート50と連通するよう構成す
る。なお、本実施例のアタッチメント用切換弁28におい
ては、スプール38の操作に際してセンタバイパス44、4
6、48が常時開となるようにスプール38の構造を設定す
る。そして、前記アタッチメント用切換弁28に設けた圧
油供給ポート50は、第１図に示すように、第１の油圧ポ
ンプ10（旋回系）と接続される供給油路52に対し、外部
配管54を介して連通接続してこれを常時開とする。ま
た、本実施例においては、第１の油圧ポンプ10（旋回
系）と接続されるバイパス開閉弁20につき、その操作部
をアタッチメント用切換弁28の操作部と連動するようパ
イロット操作回路56で接続する。このように構成するこ
とにより、アタッチメント用切換弁28を操作する際に
は、これと同時にバイパス開閉弁20が動作して第１の油
圧ポンプ10（旋回系）の圧油を供給油路52より外部配管
54を介してアタッチメント用切換弁28に供給することが
できる。However, in this embodiment, as shown in FIG. 2, the switching valve internal oil passage 36 provided in the attachment switching valve 28 is connected to the supply oil passage 34 connected to the second hydraulic pump 12 (boom system). And is normally closed, and is configured to communicate with a pressure oil supply port 50 connectable to an external pipe described later. In addition, in the attachment switching valve 28 of the present embodiment, when the spool 38 is operated, the center bypasses 44, 4
The structure of the spool 38 is set so that 6, 48 are always open. A pressure oil supply port 50 provided in the attachment switching valve 28 is connected to a supply oil passage 52 connected to the first hydraulic pump 10 (swing system) with an external pipe 54 as shown in FIG. And is normally open. Further, in the present embodiment, the operation unit of the bypass on-off valve 20 connected to the first hydraulic pump 10 (swing system) is connected by the pilot operation circuit 56 so as to interlock with the operation unit of the attachment switching valve 28. I do. With this configuration, when the attachment switching valve 28 is operated, at the same time, the bypass opening / closing valve 20 is operated to supply the pressure oil of the first hydraulic pump 10 (swing system) from the supply oil passage 52. External piping
It can be supplied to the attachment switching valve 28 via 54.
このようにして、本発明の油圧回路においては、バケ
ットとアタッチメントとをそれぞれ独立して操作する場
合、これらを駆動制御するためのブーム用切換弁24とア
タッチメント用切換弁28とは、それぞれ異なる油圧ポン
プによって独立して制御することができる。In this manner, in the hydraulic circuit of the present invention, when the bucket and the attachment are operated independently of each other, the boom switching valve 24 and the attachment switching valve 28 for driving and controlling these buckets are different from each other in hydraulic pressure. Can be controlled independently by a pump.
前述した実施例から明らかなように、本発明によれ
ば、アタッチメント用切換弁のセンタバイパスを常時開
とすると共に第２の油圧ポンプと接続された供給油路か
ら前記アタッチメント用切換弁への油路を常時閉とする
よう構成し、前記アタッチメント用切換弁と連動させて
バイパス開閉弁を操作するよう構成することにより、ア
タッチメント用切換弁を常備した油圧回路の同一制御弁
側（例えばブーム系）における他の切換弁をそれぞれ独
立して制御する際に、対応するアタッチメントとアクチ
ュエータとを確実にしかも容易に駆動制御することがで
きる。As is apparent from the above-described embodiment, according to the present invention, the center bypass of the attachment switching valve is always opened, and the oil is supplied from the supply oil passage connected to the second hydraulic pump to the attachment switching valve. By setting the path to be normally closed and operating the bypass opening / closing valve in conjunction with the attachment switching valve, the same control valve side (for example, a boom system) of the hydraulic circuit that always has the attachment switching valve is provided. When the other switching valves are controlled independently of each other, the drive of the corresponding attachment and actuator can be reliably and easily controlled.
特に、本発明によれば、実施例からも明らかなよう
に、従来のアタッチメント用切換弁の構造に大幅な変更
を加えることなく、例えば切換弁内部油路に簡単な封止
部材を設けて油路の切換えを行うことができ、またスプ
ールの一部を若干修正加工することにより容易に対応す
ることができるので、低コストで製造することができる
利点がある。さらに、アタッチメント用切換弁の操作時
には、パイロット操作回路で常設のバイパス開閉弁を連
動させてこれを簡便に操作することができる。In particular, according to the present invention, as is apparent from the embodiment, the oil can be provided by, for example, providing a simple sealing member in the oil passage inside the switching valve without making a significant change to the structure of the conventional switching valve for attachment. Since the path can be switched, and a part of the spool can be easily modified by slightly modifying the spool, it can be manufactured at low cost. Further, at the time of operating the attachment switching valve, it is possible to easily operate the permanent bypass opening / closing valve in conjunction with the pilot operation circuit.
従って、本発明の油圧回路によれば、従来のものに比
べてスペース的に縮小し得るばかりでなく、製作が容易
であり、しかもコスト的にも低減することができる等多
くの利点を有する。Therefore, according to the hydraulic circuit of the present invention, not only can the space be reduced in space as compared with the conventional one, but also there are many advantages such as easy manufacturing and reduction in cost.
以上、本発明の好適な実施例について説明したが、本
発明は前述した実施例に限定されることなく、本発明の
精神を逸脱しない範囲内において種々の設計変更をなし
得ることは勿論である。The preferred embodiment of the present invention has been described above. However, the present invention is not limited to the above-described embodiment, and it is needless to say that various design changes can be made without departing from the spirit of the present invention. .
第１図は本発明に係るアタッチメント用切換弁の油圧回
路の一実施例を示す油圧系統図、第２図は第１図に示す
アタッチメント用切換弁の構成例を示す要部断面図、第
３図は従来のアタッチメント用切換弁の油圧回路の構成
例を示す油圧系統図、第４図は第３図に示すアタッチメ
ント用切換弁の構成例を示す要部断面図、第５図は従来
のアタッチメント用切換弁の油圧回路の改善例を示す油
圧系統図である。 10……第１の油圧ポンプ 12……第２の油圧ポンプ 14……旋回用切換弁、16……アーム用切換弁 18……走行用切換弁、20……バイパス開閉弁 22……第１の制御弁、24……ブーム用切換弁 26……バケット用切換弁 28……アタッチメント用切換弁 30……走行用切換弁、32……第２の制御弁 34……供給油路、36……切換弁内部油路 38……スプール、50……圧油供給ポート 40,42……給排ポート 44,46,48……センタバイパス 52……供給油路、54……外部配管 56……パイロット操作回路FIG. 1 is a hydraulic system diagram showing an embodiment of a hydraulic circuit of an attachment switching valve according to the present invention, FIG. 2 is a sectional view of a main part showing an example of a configuration of the attachment switching valve shown in FIG. FIG. 1 is a hydraulic system diagram showing a configuration example of a hydraulic circuit of a conventional attachment switching valve, FIG. 4 is a cross-sectional view of a main part showing a configuration example of the attachment switching valve shown in FIG. 3, and FIG. FIG. 4 is a hydraulic system diagram showing an improved example of a hydraulic circuit of a switching valve for use. 10 first hydraulic pump 12 second hydraulic pump 14 swing switching valve 16 arm switching valve 18 traveling switching valve 20 bypass on-off valve 22 first Control valve 24, boom switching valve 26, bucket switching valve 28, attachment switching valve 30, traveling travel switching valve 32, second control valve 34, supply oil passage 36, ... Switching valve internal oil passage 38 ... Spool, 50 ... Pressure oil supply port 40,42 ... Supply / discharge port 44,46,48 ... Center bypass 52 ... Supply oil passage, 54 ... External piping 56 ... Pilot operation circuit
Claims (1)
閉弁を備える第１の制御弁と、第２の油圧ポンプに接続
されてアタッチメント用切換弁を含む複数の切換弁を備
える第２の制御弁とからなる油圧回路において、 前記アタッチメント用切換弁のセンタバイパスを常時開
とすると共に第２の油圧ポンプと接続された供給油路か
ら前記アタッチメント用切換弁への油路を常時閉とする
よう構成し、 前記アタッチメント用切換弁の供給油路を第２の制御弁
の外部に設けてこれを第１の油圧ポンプに接続された供
給油路と接続し、 前記アタッチメント用切換弁と連動させて前記バイパス
開閉弁を操作し該アタッチメント用切換弁の供給油路に
前記第１の油圧ポンプの圧油を供給するよう構成するこ
とを特徴とするアタッチメント用切換弁の油圧回路。1. A first control valve connected to a first hydraulic pump and having a bypass on-off valve, and a second control valve connected to a second hydraulic pump and having a plurality of switching valves including a switching valve for attachment. In a hydraulic circuit including a control valve, a center bypass of the attachment switching valve is always opened, and an oil passage from a supply oil passage connected to a second hydraulic pump to the attachment switching valve is always closed. A supply oil passage for the attachment switching valve is provided outside the second control valve, and this is connected to a supply oil passage connected to the first hydraulic pump, and is linked with the attachment switching valve. Wherein the bypass on-off valve is operated to supply pressure oil of the first hydraulic pump to a supply oil passage of the attachment switching valve. Road.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320370A JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP63320370A JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| JPH02167934A JPH02167934A (en) | 1990-06-28 |
| JP2642972B2 true JP2642972B2 (en) | 1997-08-20 |
Family
ID=18120720
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| JP63320370A Expired - Fee Related JP2642972B2 (en) | 1988-12-21 | 1988-12-21 | Hydraulic circuit of switching valve for attachment |
Country Status (1)
| Country | Link |
|---|---|
| JP (1) | JP2642972B2 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2107170A2 (en) | 1999-01-19 | 2009-10-07 | Hitachi Construction Machinery Co., Ltd. | Hydraulic driving device of civil engineering and construction machinery |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP6564754B2 (en) * | 2016-09-30 | 2019-08-21 | 日立建機株式会社 | Civil engineering and construction machinery |
-
1988
- 1988-12-21 JP JP63320370A patent/JP2642972B2/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP2107170A2 (en) | 1999-01-19 | 2009-10-07 | Hitachi Construction Machinery Co., Ltd. | Hydraulic driving device of civil engineering and construction machinery |
Also Published As
| Publication number | Publication date |
|---|---|
| JPH02167934A (en) | 1990-06-28 |
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